Evaluation of Energy Conservation Measures. for Wastewater Treatment Facilities

Transcription

1 Evaluation of Energy Conservation Measures for Wastewater Treatment Facilities EPA 832-R SEPTEMBER 2010

2 U.S. Environmental Protection Agency Office of Wastewater Management 1200 Pennsylvania Avenue NW Washington, DC EPA 832 R September 2010 Cover photo: Bucklin Point WWTF, MA. Photo courtesy of Narragansett Bay Commission. Cover insert photos (left to right): High Speed Magnetic Bearing Turbo Blower at the De Pere WTF, WI. Photo courtesy of Green Bay Metropolitan Sewerage District. Oxidation Ditch with Aeration Rotor at the City of Bartlett WWTP #1, TN. Photo courtesy of City of Bartlett Wastewater Division. Variable Outlet Vane Diffuser. Photo courtesy of Turblex, Inc. Evaluation of Energy Conservation Measures ii September 2010

3 6.4.2 Pulsed Large Bubble Mixing An innovative mixing technology by Enviromix called Bio M x reduces energy required for anoxic or anaerobic zone mixing by firing short bursts of compressed air into the zone instead of mechanically mixing it. Uniquely designed nozzles produce a mass of large air bubbles, ranging from marble to softball size, which mix the water as they rise to the surface (Randall and Randall 2010). The large air bubbles, much larger than those made by coarse bubble diffusers, are designed to minimize oxygen transfer and maintain anoxic or anaerobic conditions. The system includes a PLC to manage the timing of the air control valve firing, which gives the operator flexibility to respond to different conditions within the tank. The manufacturer reports that the system has non clogging, self cleaning in tank components that require no maintenance. See Figure 6 4 for a typical installation and the manufacturer s website for additional information ( mix.com/biomx.php). Figure 6 4. Typical BioMix TM Installation Source: EnviroMix. Used with permission An independent study at the F. Wayne Hill Water Resources Center in Gwinnett County, Georgia compared the performance and energy use of Bio M x to submersible propeller mixers (Randall and Randall 2010). The plant, treating 30 mgd on average with a design flow of 60 mgd, operates up to 10 parallel treatment trains each with anaerobic, anoxic, and aerobic zones for biological nitrogen and phosphorus removal. In the spring of 2009, the Bio M x system was installed in two anaerobic cells of one treatment train. The system consisted of an Ingersoll Rand 5 15 hp variable speed rotary screw compressor, piping, controls, and floor mounted nozzles. Findings from the technology evaluation performed in January 2010 are summarized below. Dye tracer tests showed similar mixing for the Bio M x and submersible mixer systems. Total suspended solids (TSS) profiles showed that the Bio M x unit is capable of mixing to homogeneity similarly to the submersible mixing units, although variability in the Bio M x cells was slightly higher. Evaluation of Energy Conservation Measures 6 12 September 2010

4 Continuous oxidation reduction potential (ORP) measurements over periods of 12 to 28 hours showed 95 th percentile ORP values of less than 150 millivolts (mv), which is indicative of anaerobic environments. Given the success in anaerobic environments (< 100 mv), the technology is also applicable for use in anoxic environments. Power analyzer readings taken simultaneously showed that energy (in kw) required to mix one anaerobic cell using the Bio M x system was 45 percent less than the energy required by a submersible mixer. When operated in three cells using the same compressor, 60 percent less energy was required (0.097 hp/1000 cf) The manufacturer also presents test results conducted from April 2009 through February 2010, available online at mix.com/documents/fwaynehillenergysuccessstory pdf. 6.5 References Cooper, N., J. Marshall, K. Hunt, and J. Reidy Less Power, Great Performance System modifications shrink a Georgia membrane bioreactor s power demand. Water Environment & Technology. Alexandria, VA: WEF. 19(2): Efficiency Partnership Water/Wastewater Case Study: Central Contra Costa Sanitary District. Flex Your Power. Retrieved January 27, Faber, J communication to the author. March 26, Fillos, J. and K. Ramalingam Evaluation of Anoxic Zone Mixers at the Bowery Bay WPCP. New York City Department of Environmental Protection, Process Planning Section, Division of Operations Support, Bureau of Wastewater Treatment. Contract # PW 047. Gidugu, S., S. Oton, and K. Ramalingam Thorough Mixing Versus Energy Consumption. New England Water Environment Association Journal, Spring Ginzburg, B., J. Peeters, and J. Pawloski On line Fouling Control for Energy Reduction in Membrane Bioreactors. Presented at Membrane Technology Atlanta, GA. WEF. Leong, L.Y.C., J. Kuo, and C Tang Disinfection of Wastewater Effluent Comparison of Alternative Technologies. Water Environment Research Foundation (WERF), Alexandria, VA. Lim, A.L. and R. Bai Membrane Fouling and Cleaning in Microfiltration of Activated Sludge Wastewater. Journal of Membrane Science. 216 (2003), Pacific Gas and Electric Company (PG&E) Energy Benchmarking Secondary Wastewater Treatment and Ultraviolet Disinfection Processes at Various Municipal Wastewater Treatment Facilities. San Francisco, CA. Available online at sys/ww/pge2.pdf. Peeters, J., J. Pawloski and J. Noble The evolution of immersed hollow fibre membrane aeration for MBR, IWA 4th International Membrane Technologies Conference, Harrogate, UK. Peng, J., Y. Qiu, and R. Gehr Characterization of Permanent Fouling on the Surfaces of UV LampsUsed for Wastewater Disinfection. Water Environ. Res. 77(4), Evaluation of Energy Conservation Measures 6 13 September 2010

5 Phillips, D. L. and M. M. Fan Automated Channel Routing to Reduce Energy Use in Wastewater UV Disinfeciton Systems. University of California, Davis. Davis, California. Randall, C.W. and W. O. Randall Comparative Analysis of a Biomix System and a Submersible Propeller Mixer: Mixing in Anaerobic Zones at the F. Wayne Hill Water Resources Center, Buford, Georgia. Report provided in an e mail from Clifford W. Randall to the author on May 4, Salveson, A., T. Wade, K. Bircher, and B. Sotirakos High Energy Efficiency and Small Footprint with High Wattage Low Pressure UV Disinfection for Water Reuse. Presented at the International Ultraviolet Association (IUVA)/ International Ozone Association(IOA) North American Conference. May 5, Boston, MA USEPA Wastewater Technology Fact Sheet: Ultraviolet Disinfection. Office of Water. EPA 832 F Available online at USEPA Ultraviolet Disinfection Guidance Manual for the Final Long Term 2 Enhanced Surface Water Treatment Rule. Office of Water. EPA 815 R Available online at Wallis Lage, C.L. and S. D. Levesque Cost Effective & Energy Efficient MBR Systems. Presented at the Singapore International Water Week. June 22 26, Suntec Singapore International Convention and Exhibition Center. Available online at lage.pdf WEF and ASCE Design of Municipal Wastewater Treatment Plants WEF Manual of Practice 8 and ASCE Manuals and Reports on Engineering Practice No. 76, 5th Ed. Water Environment Federation, Alexandria, VA, and American Society of Civil Engineers Environment & Water Resources Institute, Reston, Va. WEF MOP No. 32: Energy Conservation in Water and Wastewater Facilities. Prepared by the Energy Conservation in Water and Wastewater Treatment Facilities Task Force of the Water Environment Federation. McGraw Hill, New York. Evaluation of Energy Conservation Measures 6 14 September 2010